Microstructured transmission and reflectance modifying coating

In an article comprising a transparent flexible substrate having thereon a coating of boehmite, the improvement wherein the coating is characterized by a plurality of closely spaced and randomly positioned discrete leaflets of varying heights and shapes, which leaflets extend from the substrate a distance of not less than 20 nm nor more than the wavelength of visible light, and the bases of which contact the bases of substantially all adjacent leaflets to provide the article with a total specular reflectance of visible light incident normal to the surface coating of less than one percent, and a transmissivity of said normal incident light of not less than 98%, and wherein the surface coating is substantially hydrophilic, whereby the particles may be useful as optical lenses, solar absorbers, photovoltaic cells and the like such that the reflectance is decreased and transmissivity is enhanced over similar but uncoated articles to enable greater amounts of light and/or radiant energy to be passed therethrough.

A grooved Fresnel-type lens comprising a polymeric body having on at least one surface thereof an array of grooves forming a Fresnel-type lens and having on at least the grooved surface a coating of an oxide or hydroxide of a metal selected from the group consisting of aluminum, magnesium and zinc or alloys thereof, which coating is a substantially complete conversion of a thin-film of said metal, the thickness of said thin-film prior to conversion being at least 5 nanometers and exhibiting a surface after said conversion characterized by a plurality of randomly positioned discrete leaflets of varying heights and shapes, which leaflets extend from the surface a distance of not less than 20 nanometers nor more than the wavelength of light, and the bases of which contact the bases of substantially all adjacent leaflets to appreciably reduce the specular reflection of visible light directed toward said coating.